1. Field of the Invention
The present relates to an ink-jet printing apparatus for carrying out the printing operation by ejecting ink from printing means onto a printing medium.
2. Description of the Related Art
Recording apparatuses having functions of a printer, a copying machine, a facsimile recorder or others or those used as an outputting device for a composite type electronic equipment or a work station such as a computer or a word processor are adapted to print images on a printing medium such as paper, cloth or plastic sheet. The printing apparatuses may be classified into an ink-jet type, a wire dot type, a thermal type, a laser beam type or others in accordance with the printing methods.
According to a serial type printing apparatus wherein a serial scanning system is adopted, after the printing medium has been set at a predetermined printing position, an image is scanned along the printing medium by a printing means carried on a carriage (a main scanning), and after the printing of one line has finished, a predetermined amount of the printing medium is conveyed (a sub-scanning) and stopped. Then, an adjacent image is scanned and printed again on the stopped printing medium. By repeating these motions, printing on the entire printing medium is carried out. On the other hand, there is a printing apparatus of a line type using printing means having printing elements arranged in a range corresponding to a width of a printing medium, capable of carrying out the printing operation solely by the sub-scanning in the conveying direction. In this apparatus, the printing medium is first set at the predetermined printing position, and after the printing of one line has been at once completed, the predetermined amount of the printing medium is fed (the pitch feed). Then, the printing of the next one line is carried out at once. According to the repetition of such operations, printing all over the printing medium is completed.
Of the above-mentioned printing systems, a printing apparatus employing the ink-jet system (the ink-jet printing apparatus) carries out the printing operation while ejecting ink from printing means (a printing head) onto a printing medium, and has advantages in that the printing means is capable of being easily small-sized; a high-precision image is printed at a high speed; the printing is carried out on a so-called normal paper which has not been subjected to a special treatment whereby a running cost is reduced; the noise generation is less because of a non-impact system; and it is easily adaptable to the printing of color images using multi-color inks.
There are a serial type and a line type in the above ink-jet printing apparatus. In the former type, an image is formed by alternately repeating the main printing scan in which the printing operation is carried out while subjecting printing means (a printing head) including a plurality of printing elements (ejection orifices) to the scanning motion relative to a printing medium with the sub-scan in which the printing medium is conveyed in the direction vertical to that of the main printing scan. This type is suitable for a personal use and has been widely marketed because it is inexpensive in production cost and small in size. On the other hand, in the latter type, a so-called full multiple type printing head is used, in which a number of ejection orifices are arranged in the widthwise direction of the printing medium, and an image is completed by moving the printing medium in the direction different from the arrangement of the ejection orifices. Although the printing apparatus is large in size and relatively expensive since the printing head becomes longer, this type is superior to the serial type in the printing speed.
In this regard, there are various ejection systems in the printing head employing the ink-jet system. Particularly, the printing head of the ink-jet system for ejecting ink by utilizing thermal energy is capable of realizing the high precision and high speed of the printing as well as further compacting the printing apparatus used therefor, because a number of liquid passages or ejection orifices is easily and precisely manufactured on a substrate through processes similar to those for producing a semiconductor device, such as etching, depositing or sputtering to form electro-thermal transducers, electrodes, liquid passage walls or top plates.
Generally speaking, according to such an ink-jet printing apparatus, a device is often added for carrying out the recovery action (recovery operation) for maintaining or recovering the stable ink ejection performance. The recovery action includes a wiping for removing viscous ink or paper powder adhered to an area in the vicinity of the ejection orifice by wiping the ejection orifice-forming surface of the printing head with a wiping member, a suction recovery for forcibly sucking viscous ink or air bubble from the interior of the printing head by applying a suction force to the printing head, and a preliminary ejection for ejecting viscous ink from the liquid passages not used during the printing operation to replace it with fresh ink.
In this regard, the suction recovery is carried out by capping the ejection orifice-forming surface and applying a negative pressure thereto to forcibly suck the ink from the ejection orifices. As means for carrying out such a recovery operation, the printing apparatus is generally provided with a pump. The pump may be a so-called tube pump using a roll moving while collapsing a flexible tube or a piston pump having a piston moving in a cylinder, and a relatively large amount of waste ink is generated in the recovery operation.
The waste ink generated by the recovery operation is introduced from the recovery device to a waste ink absorber provided within a main body of the printing apparatus and is retained there while taking care not to leak outside. The waste ink absorber is often a sheet member of fibers excellent in ink absorbency and diffusivity due to the capillary action.
FIG. 1 is a perspective view illustrating the conventional ink-jet printing apparatus.
The illustrated ink-jet printing apparatus includes a paper-feed section 10 for feeding a printing medium one by one to a conveying section 20 within a main body of the printing apparatus, the conveying section 20 for guiding the printing medium to a predetermined printing position and then discharging the same therefrom, a discharging section 30 located downstream from the conveying section 20, a printing section 40 for carrying out the printing operation in accordance with image data on the printing medium conveyed by the conveying section 20, a recovery section 60 for carrying out the recovery treatment for the printing section 40 or others, and a chassis 71 for supporting these sections to construct the integral printing apparatus.
FIG. 2 is a perspective view for illustrating the arrangement of the recovery section 60 of the ink-jet printing apparatus 60 and the waste ink absorber. In the conventional ink-jet printing apparatus, the waste ink absorber 64 is disposed on a lower case 4 beneath the recovery section 60 as a layout within the apparatus, for receiving the waste ink generated while being accompanied with the recovery operation, diffusing the same into the absorber 64 due to the capillary action of the absorber-forming material, and retaining the ink while evaporating solvent.
It has recently been desired that the ink-jet printing apparatus is further small-sized to have a high-portability. To satisfy such a requirement, a height (a thickness) of the apparatus body is preferably as small as possible. However, the conventional structure in which the waste ink absorber is disposed beneath the recovery device has been a bottleneck for designing such a thin type printing apparatus. Also, the inconvenience in that the waste ink is leaked out from the apparatus should be avoided for the purpose of improving the portability, even if the apparatus is transported or conveyed in any orientations.